The North American High (also Canadian High/Anticyclone, sometimes in Europe Greenland High/Anticyclone) is an impermanent high-pressure area or anticyclone created by anticyclogenesis (anticyclone + the Greek word genesis, meaning "birth, origin"), a formative process that occurs when cool or cold dry air settles over North America.
North American Highs moves eastwards across the continent, often in the company of one or more low-pressure cells or cyclones. Its cold, dense air does not extend usually above 3 km (1.9 mi), lower than the Canadian Rockies. Sometimes, in winter it breaks free and passes over the Rockies and brings a cold front into Southwestern United States and Mexico, freezing crops and bringing snow into Mexico's mountains as far south as Jalisco. The high’s usual location east of the Rockies shelters it from the relatively warm Pacific Ocean and helps it maintain its strength. The average January sea level pressure at its centre is about 1,020 millibars (30.12 inches of mercury). The Canadian high often moves southeastward until it eventually reaches the Atlantic Ocean, where it merges with the Azores high. In the summer the Canadian high circulates cool, dry air to the United States east of the Rockies and parts of southern Canada.
The North American High is akin to the Siberian High of Eurasia, but it is much smaller, and it has much less influence, merely affecting the weather of the Northern Hemisphere. The sea-level pressure (atmospheric pressure) rarely, if ever, exceeds 1055.0 millibars (1055.0 hectopascals)(hPa)(SI).
Often, in the winter months, cool or cold dry air settles over the land in the vicinity of the Great Basin where it builds into a high-pressure cell or anticyclone that moves across the United States with a cold front on its leading edge. After reaching the Atlantic Ocean, the moist environment brings on changes of the qualities of the air and the dissipation of the high-pressure cell or anticyclone as the cold air warms and becomes humid. The slow decay and disappearance of an anticyclone is called anticyclolysis (anticyclone + the Greek word lyein, meaning "to dissolve"; it is used to form many other words, such as paralysis, e.g).
In Europe, a portion of the North American/Canadian high usually over Greenland called the Greenland high which settles over Greenland affects northern European weather and may merge with the Scandinavian High.
Famous quotes containing the words north american, north, american and/or high:
“Civilization does not engross all the virtues of humanity: she has not even her full share of them. They flourish in greater abundance and attain greater strength among many barbarous people. The hospitality of the wild Arab, the courage of the North American Indian, and the faithful friendships of some of the Polynesian nations, far surpass any thing of a similar kind among the polished communities of Europe.”
—Herman Melville (1819–1891)
“I know no East or West, North or South, when it comes to my class fighting the battle for justice. If it is my fortune to live to see the industrial chain broken from every workingman’s child in America, and if then there is one black child in Africa in bondage, there shall I go.”
—Mother Jones (1830–1930)
“The compulsion to do good is an innate American trait. Only North Americans seem to believe that they always should, may, and actually can choose somebody with whom to share their blessings. Ultimately this attitude leads to bombing people into the acceptance of gifts.”
—Ivan Illich (b. 1926)
“Who is the happy Warrior? Who is he
That every man in arms should wish to be?
It is the generous spirit, who, when brought
Among the tasks of real life, hath wrought
Upon the plan that pleased his boyish thought:
Whose high endeavors are an inward light
That makes the path before him always bright:
Who, with a natural instinct to discern
What knowledge can perform, is diligent to learn;
And in himself posses his own desire;”
—William Wordsworth (1770–1850)